Off-pump coronary artery bypass graft surgery: Collaborative Targeted Maximum Likelihood Estimation

Background: There is some discrepancy about the superiority of the off-pump coronary artery bypass grafting surgery to the conventional cardiopulmonary bypass (on-pump). We aimed to estimate the ratio of mortality risk in the off-pump coronary bypass to the on-pump by a causal model known as Collaborative Targeted Maximum Likelihood Estimation. Study design and method: The data of the Tehran Heart Cohort study from 2007 to 2020 was used and analyzed. A collaborative targeted maximum likelihood estimation and targeted maximum likelihood estimation were used to estimate an adjusted risk ratio for the minimum sufficient set of confounders in a sequential approach. The results of these methods were compared to the traditional ones. Results: Among 24883 participants (73.6% male), 5566 patients died during 8.2, on average, years follow-up. The estimated relative risk (95% confidence intervals) by un-adjusted general linear model, propensity matching, targeted maximum likelihood estimation, and Collaborative Targeted Maximum Likelihood Estimation was 0.86 (0.78-0.95), 0.88(0.8-0.97), 0.88 (0.8-0.97), and 0.99 (0.98-1.01), respectively. Conclusion: Our analysis revealed that both techniques of surgery are safe and equally effective and there is no significant difference regarding mortality risk between the two techniques.